1. Field of the Invention
The invention concerns a circuit arrangement for telephone communication installations. The latter comprises a central control unit and individual apparatus of different types; for example, internal connection sets, long distance line repeaters, exchange office repeaters in subscriber installations with extension stations, registers, dial receivers and the like. Correspondingly, different information and different types of information, for example dial impulse series, control signals and the like are exchanged between the central control unit and the individual apparatus.
2. Description of the Prior Art
In recent times many exchange installations of this type having central control means, e.g., special purpose control computers, have become known in the telephone art. To a plurality of individual apparatuses there is assigned a common apparatus, also designated as central control unit, which exchanges information with the individual apparatuses and carries out the largest part of the logical information processing for these apparatuses. Due to this centralization of the logical function of an exchange installation, the total expenditures therefore, may, as is known, be considerably increased. However, changes in the mode of functioning can advantageously be made in exchange installations of this type as appropriate circuitry changes need only be made at the central location.
Thus, circuitry requirements are to a great extent centralized in centrally controlled exchange installations. The individual apparatuses are developed in such a way that they require the least possible expenditures. Their operating speed is also relatively low, because of the circuit conditions of lines and to switching devices included in connections. In contrast, the central control means has a very much higher operating speed, as it must work with all of the individual apparatuses in succession. Even the extent of its operational range depends on its operating speed; the faster its functional programs are carried out, the more individual apparatus can be served by a single central control means.
The time requirements for each functional program of the central control means include information reception, logical information processing, and information transmission. To speed up the functional programs of a central control unit, only the time requirement for the information processing can be restricted, if it is equipped with appropriately fast working switching devices. However, the time requirement for information reception and transmission depends on those of the individual apparatuses with which the central control means is, at the time, exchanging information. To reduce the time requirements for the functional programs of the central control unit there have, therefore, previously been provided buffer stores between it and the individual apparatus with which exchanges of information are carried out.
With regard to the above, reference is made to U.S. Pat. No. 3,113,184. In this patent the individual apparatus consists of coupling groups of a switching matrix. To each coupling group one buffer store each is assigned. Two types of coupling groups are provided, i.e., subscriber coupling groups and connection line coupling groups. Accordingly, two types of information collector lines are provided between the buffer stores and the central control means. Depending on their assignment to subscriber coupling groups or to connection line coupling groups, the buffer stores are connectable to one of two information collector lines with the aid of gate circuits individually assigned to the buffer stores. These gate circuits are corresponding to the two types of coupling groups controllable from the direction of the central control unit over two separate multiple control lines which are provided in addition to the information collector lines, so that in each case only a single buffer store is connectible to the information collector line leading to the central control.
A prominent characteristic of the known arrangement thus resides in the fact that the address of the individual apparatus to be connected in each case to the central control unit lies in a control command transmitted by the central control unit over the multiple control line. The type of the individual apparatus in question is expressed, not in its address, but in the use of the multiple control line and information collector line in each case, over which the information transmission is prepared and carried out.
It must also be considered that the further individual apparatus in the known arrangement, i.e., subscriber line circuits (subscriber circuits), connection line circuits (connection sets for internal and external connections) and announcement registers (customary dial receiving registers), contain storage means, as the central control unit cannot receive arbitrarily the information collecting therein, but it must also control the information exchange with these individual apparatuses so that it can be carried out gradually. It must further be assumed as a matter of course that just as the switching matrix is developed of many individual apparatuses (coupling groups), there are also provided several connection sets each for internal and external connections, several registers each, etc. Thus for these individual apparatuses too the previously stated principle that in the known arrangement the address of the individual apparatus to be connected in each case to the central control unit lies in a control command transmitted by the central control unit over the control multiple line, whereas the type of the individual apparatus in question is expressed not in its address, but in the use of the multiple control line and information collector line in each case, over which the information transmission is prepared and carried out.
The individual apparatuses are, among others, those from which the central control unit must receive information, which differs not only in the address of the individual apparatus from which they originate, but also in their type; for example, there are offered to the central control unit on one hand by registers - dial signals, and on the other hand, by connection sets - line signals received therein. Such different information is distinguishable with regard to the specimen of the individual message, in each case by its address, but with regard to its specific type (connection set, register) only with the aid of the specific multiple information. Thus, in the known arrangement several multiples of information are required for the central control unit so that it can distinguish the various types.